Stimulatory effect of arachidonic acid on T-47D human breast cancer cell growth is associated with enhancement of cyclin D1 mRNA expression

Experimental and human studies have provided evidence that a high intake of n-6 polyunsaturated fatty acids stimulates mammary carcinogenesis. Arachid onic acid, an n-6 fatty acid consumed in the diet or derived from dietary l inoleic acid, is thought to play a key role in enhancement of mammary tumor development. In this study; we investigated the effects of arachidonic aci d on T-47D breast cancer cell growth, cell cycle progression, and the expre ssion of cyclin DI mRNA. Our data show that arachidonic acid stimulated the growth of T-47D cells with a twofold stimulation at 5 mug/ml. This effect was associated with an increase in the proportion of cells in the S phase o f the cell cycle and preceded by stimulation of the expression of cyclin DI mRNA, with maximal induction at 5, mug/ml. Cyclin DI mRNA levels were incr eased within two hours of treatment and were maximal at five hours. These r esults suggest that arachidonic acid may exert a stimulatory effect on brea st cancer cell growth and that this effect possibly involves the induction of cyclin DI gene expression leading to cell cycle progression.